Peripheral Nerve Function Decline in an Aged Cohort

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DESCRIPTION (provided by applicant): Although poor peripheral nerve function is common in older age, the rate of decline with aging is unknown. Diabetes and other known causes of neuropathy appear to account for very little of the loss of nerve function with advancing age. We conducted a cross-sectional epidemiologic study of the prevalence and risk factors or poor peripheral sensory and motor nerve function in the Health, Aging and Body Composition (Health ABC) cohort. The Health ABC baseline cohort included 3075 men and women (42 percent African-American and 52 percent women). Of these, 1462 survivors aged 80-89 years of age are expected for their eleventh year follow- up exam. Longitudinal data from 2000-01 to 2007-08 will make it possible to determine whether nerve function declines are related to prospective lower extremity disability in 2008-10 and whether or not these associations are mediated by changes in muscle, bone density, and strength. We have documented cross- sectionally that peripheral nerve function is critical to their lower extremity function and mobility and is associated with muscle strength and bone density, demonstrating the importance of the peripheral nerves in sarcopenia and age-related disability. Analyses of numerous potential risk factors in Health ABC have revealed that age itself remains strongly related to poorer peripheral nerve function, even when accounting for established risk factors such as diabetes, and novel risk factors such as subclinical peripheral arterial disease and Caucasian race. To date, no U.S. study has reported the rate of decline in these aspects of peripheral nerve function with aging or has determined whether they precede lower extremity disability. The specific aims are to determine 1) declines in peripheral sensory and motor nerve function over six years and risk factors for these declines (demographic factors, vitamin B12 status, impaired glucose metabolism, subclinical peripheral arterial disease) in Caucasian and African-American older adults; and 2) if the rate of decline in peripheral sensory and motor nerve function is prospectively related to rate of recurrent falls and a decline in self-reported walking ability over two years. This study addresses many goals of the NIA, defined in its strategic plan, including prevention of disability, understanding age-related change and evaluating ethnic disparities. The Health ABC Study provides a unique and cost-effective opportunity to quantify and identify risk factors for decline in sensory and motor nerve function and relate these declines to prospective disability for the first time among a large group of older adults.